This study has two goals: (1) Prevalence. To ascertain the prevalence rates of severe mental disorder among 750 randomly selected female jail detainee in Cook County Department of Corrections (CCDC) in chicago, Illinois. We will determine if the rates of severe mental disorder are significantly different than baseline population rates ascertained by the Epidemiologic Catchment Area (ECA) Project; (2) Detection and Treatment. To explore the extent that mentally ill female jail detainee are detected and treated while in jail. We will determine at which point in the process the detainee is treated and which variables, such as violent behavior or suicidal ideation, determine referral and treatment decisions. Prior studies of mental disorder among female offender samples suffer from four methodological limitations. First, few studies use random samples. Second, samples were too small to generate reliable rates of serious mental disorders. Third, many studies used unspecified diagnostic criteria and/or nonstandardized instruments to assess mental disorder. Finally, because no study has systematically compared its findings to baseline (population) rates, we cannot know if the observed rates of mental disorder are greater than would be expected by chance. This study has four methodological advantages over prior epidemiologic work: (1) a random sampling strategy; (2) a sufficiently large N (750) to generate reliable prevalence rates; (3) a reliable method of diagnosis (the NIMH Diagnostic Interview Schedule); and (4) baseline comparisons with the general population (ECA). Reliable data on female offenders is critical because both the volume of female crime particularly violent crime, and the number of incarcerated females are increasing at a faster rate than among males. The prevalence data will help us put the system's scarce resources to their best use. Psychiatric treatment of mentally ill jail detainee is mandated by law. Without accurate prevalence rates, however, we cannot know how best to use the criminal justice system's scarce resources. Accurate prevalence rates will point to appropriate rehabilitation strategies designed to treat the most common diagnostic profiles. The detection and treatment information will document how mentally ill female jail detainee are managed while in the custody of the criminal justice system. Before making public policy changes, we need to know how mentally ill jail detainee are currently treated. These data will aid in planning health delivery strategies within the mental health and criminal justice systems, as well as suggest viable alternatives to incarceration for mentally ill female jail detainee.